Diffraction‐Based Strategy for Monitoring Topographical Features Fabricated by Direct Laser Interference Patterning

• Published in: Advanced engineering materials 2023-07, Vol.25 (13), p.n/a
• Main Authors: Schröder, Nikolai, Fischer, Christoph, Soldera, Marcos, Voisiat, Bogdan, Lasagni, Andrés Fabián
• Format: Article
• Language: English
• Subjects: diffraction; direct laser interference patterning; monitor; period; scatterometry; structure depths
• ISSN: 1438-1656; 1527-2648
• DOI: 10.1002/adem.202201889

Process monitoring in laser‐based manufacturing has become a forward‐looking strategy for industrial‐scale laser machines to increase process reliability, efficiency, and economic profit. Moreover, monitoring techniques are successfully used in laser surface texturing workstations to improve and guarantee the quality of the produced workpieces by analyzing the resulting surface topography. Herein, dot‐like periodic surface structures are fabricated on stainless steel samples by direct laser interference patterning (DLIP) using a 70 ps‐pulsed laser system at an operating wavelength of 532 nm. A scatterometry‐based measurement device is utilized to indirectly determine the mean depth and spatial period of the produced topography by analyzing the recorded diffraction patterns. As a result, the average depth and the spatial period of the dot‐like structures can be estimated with a relative error below 15% and 2%, respectively. This new process monitoring approach enables a significant improvement in quality assurance in DLIP processing. Herein, dot‐like structures with variable mean structure heights and spatial periods are fabricated on stainless steel using direct laser interference patterning. An advanced monitoring system based on scatterometry is successfully applied to determine the structure depth and spatial period with mean errors below 15% and 2%, respectively.